The use of QLF to quantify in vitro whitening in a product testing model

Abstract

RESEARCHaesthetic dentistry to practitioners, many do not offer such procedures. Patients must therefore use 'at-home' products to achieve tooth colour change, typically through the removal of extrinsic stain. The majority of these products are marketed as tooth-whitening dentifrices.The causes of extrinsic tooth staining are complex and have been covered in the literature recently. 4 The method of action of these pastes is believed to be a combination of mechanical and chemical effects. 5 Research has assessed both of these modalities, with the current study concentrating on the chemical properties. 6 In order to properly assess these toothpastes a number of studies have been performed. One of the most comprehensive was by Sharif et al. 5 The techniques used in Sharif's paper were developed by Addy and involve the use of stained Perspex with spectrophotometer analysis. 7 The strengths of such a technique include the ability to control the application of the stain, the exposure of the test product to the specimen and also to longitudinally monitor any reduction in stain.However, it would be ideal to retain these experimental strengths while using a more authentic stained substrate, human enamel. Using a new technology for the detection of early carious lesions, the current study describes such a technique. Quantitative light-induced fluorescence (QLF)The detection of very early (and hence reversible) carious lesions by optical methods has been a major research focus of cariologists. 8 One of the most promising devices is the QLF (Inspektor Research Systems BV, NL). 9,10 The underlying principle of the QLF technique is that teeth will auto-fluorescence under certain light conditions, and that demineralised enamel will fluoresce less than sound enamel. When examined under the QLF, demineralised lesions appear as dark areas. With analytical software, the loss of fluorescence characteristic of demineralised areas can be compared with the unaffected fluorescence of the sound enamel and a quantifiable value, ∆Q, reported. Developed from early experimentation with lasers, the QLF device has been the subject of numerous validation articles. 11,12 The QLF handpiece is shown in Figure 1. QLF and staining Amaechi has described the potential for QLF to quantify stain removal. 13 The stain produced on the teeth appears on the QLF image in a similar manner to demineralised lesions. The analytical software is able to compare the stained enamel to adjacent unstained enamel in the same way as demineralised and sound enamel is compared. This study furthers the initial work by incorporating it into a product-testing model. By employing this mechanism a longitudinal and quantifiable analysis of stain reduction on human enamel specimens is possible. Materials and methodsA total of 11 previously extracted human mandibular third molars were selected. Buccal surfaces were devoid of intrinsic stain, enamel cracks or fractures, caries or other enamel defects. The teeth were gently pumiced and their buccal surfaces gently abraded with wet...

Impact of Streptococcus mutans on the generation of fluorescence from artificially induced enamel and dentin carious lesions in vitro

“…Caries diagnostic devices using laser/light-induced fl uorescence detection systems, such as the DIAGNOdent 13-15 and QLF, [16][17][18] have been clinically studied, and promising results has been reported; 19,20 however, the mechanism of fl uorescent refl ection from carious lesions remains unclear. In this study, the relationship between the presence of intra-oral bacteria (S. mutans) and fl uorescence signals was investigated by using artifi cial demineralization models.…”

“…[13][14][15] Another type of fl uorescence device, quantitative light-induced fl uorescence (QLF), measures the fl uorescence induced by blue light illumination with wavelengths of around 405 nm. [16][17][18] It should be noted, however, that fl uorescence from carious lesions differs depending on the carious condition and that the primary origin of fl uorescence signals has not yet been fully determined.…”

Quantification of dental plaque in the research environment

“…34 Considerable interest surrounds the device and recent applications have included the assessment of decalcification adjacent to orthodontic brackets, dental erosion, tooth whitening, root lesions, and secondary caries. 30,[35][36][37] An investigation into the ability for QLF to determine plaque was conducted.…”

Comparison of quantitative light-induced fluorescence (QLF) and digital imaging applied for the detection and quantification of staining and stain removal on teeth

“…QLF is an optical method that uses the natural fluorescence of teeth to distinguish between sound enamel and caries but it can also be used to detect stains in a similar manner. 15,16 There have been studies describing the detection of stain removal, although none have investigated the longitudinal monitoring of extrinsic stains. 15,16 This study has shown that QLF is an appropriate technique to longitudinally detect and quantify stain development and monitor bleaching in vitro.…”

“…15,16 The stain produced on the teeth when imaged using QLF has a similar appearance to demineralised lesions. By employing QLF it is possible to monitor and quantify longitudinally the analysis of stain and stain reduction on enamel.…”